Electrophoresis is a well-known technique for separating macromolecules. In an electrophoretic application, molecules in a sample to be tested are migrated in a medium across which a voltage potential is applied. The sample is propagated through a gel which acts as a sieving matrix to help retard and separate the individual molecules as they migrate. Oftentimes, a capillary tube (hereinafter "capillary") is provided for holding the gel and for allowing the sample to migrate therein.
A conventional capillary electrophoresis device (CED) 10 provided with a plurality of capillaries is depicted in FIG. 1. The conventional CED 10 includes an electrode/capillary array 11, multilumen tubing 13, tubing holders 15, optical detection region 17, capillary bundle 19 and high pressure T-fitting 21. The capillaries have sample ends disposed in the electrode/capillary array 11 and second ends received by the high pressure T-fitting 21.
The electrode/capillary array 11 includes electrodes and the sample ends of capillaries protruding from the bottom side of the CED. The electrodes and the sample ends of capillaries are arranged to be dipped into corresponding sample wells in a 96-well or a 384-well microtitre tray; this requires 96 or 384 capillaries in order to fully utilized every well on the microtitre tray. (The microtitre tray is not illustrated in FIG. 1.)
The capillaries run inside of corresponding multilumen tubes 15 which are firmly fixed in place by the tubing holders 15. Exposed portions of the capillaries, lined up side-by-side and without the protection of multilumen tubing, then pass through the optical detection region 17, which includes a CCD camera assembly (not shown in FIG. 1). The CCD camera assembly captures images of samples traveling inside the exposed capillaries. The exposed second ends of the capillaries are then bundled together and fitted into the high pressure T-fitting.
The above described conventional CED is utilized to perform electrophoresis runs. An exemplary electrophoresis run may include the steps of: conditioning and preparing the capillaries by washing capillaries by injecting wash solutions to the capillaries and refilling the capillaries with gels; introducing samples to the samples ends of the capillaries when the capillaries are conditioned properly to receive the samples; applying a voltage potential, i.e., 12 KV, between the sample ends of the capillaries and the high pressure T-fitting; and capturing images of the samples as they travel inside capillaries by the CCD camera at the optical detection region. A plurality of valves and pumps are provided to the CED in order to properly carry out the washing, reconditioning and refilling cycles with appropriate liquid solutions.
More detailed description of the above features are described in U.S. patent application Ser. No. 09/105,988, which is incorporated herein in its entirety by reference.
An operator of the conventional CED, however, is required to monitor closely the CED during electrophoresis runs. For instance, liquid containers holding wash solutions to be injected into the capillaries must be checked constantly and replenished when the wash solutions are depleted. During an electrophoresis run the operator is also required to be aware of which cycle the electrophoresis run is performing, because each cycle demands the operator to perform different manual tasks. For example, after the capillaries are conditioned with the gel, the operator is required to check the sample tray and the capillaries before applying the voltage potential. This is because if sample tray is not present or if capillaries are not filled with the gel, then applying the voltage potential to the capillaries may damage the CED.
Moreover, this task of manually checking the capillaries is a laborious task, because a small impurity in the gel inserted into the capillaries or an air bubble in the capillaries can cause damage to the CED, and it may also cause the electrophoresis run to be ruined with an unusable data collection. When the samples are abundant, one unsuccessful run is not a problem; however, when the sample are rare samples then one unsuccessful run is catastrophic. In order to reduce the risk, the operator is required to check the capillaries carefully, which is time consuming and tedious. In view of the above shortcomings, what is needed is a system to automatically and monitor and regulate the CED.